[10] RFR(S) 8186462: [Graal] build Graal regardless AOT build

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8186462/webrev/
https://bugs.openjdk.java.net/browse/JDK-8186462
We are planning to have Graal as experimental JIT compiler on linux-x64 
in next release. For that we should enable its build independent from 
AOT build.

Thanks,
Vladimir